Description
A type confusion in jsish 2.0 allows incorrect control flow during execution of the OP_NEXT opcode. When an “instanceof” expression uses an array element access as the left-hand operand inside a for-in loop, the instructions implementation leaves an additional array reference on the stack rather than consuming it during OP_INSTANCEOF. As a result, OP_NEXT interprets the array as an iterator object and reads the iterCmd function pointer from an invalid structure, potentially causing a crash or enabling code execution depending on heap layout.
References
https://blog.mcsky.ro/writeups/2025/11/15/inline8-writeup.html
https://blog.mcsky.ro/writeups/2025/11/15/inline8-writeup.html
Weaknesses
134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS impact metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8 · Critical
Information
Source identifier
Vulnerability status
Analyzed
Published
2025-12-29T14:16:01.763Z
3 weeks agoLast modified
2025-12-31T19:04:10.750Z
3 weeks ago